Real Trouble In The Arctic

On the heels of yesterday's back-handed good news on the Amazon come this pair of troubling reports from NASA on Arctic ice. In the first, melting sea ice has now shrunk so far below the minimum set in 2005 that researchers, speaking between the lines, clearly fear we may have already passed a tipping point. From Waleed Abdalati, head of NASA Goddard's Cryospheric Sciences Branch:

This year, the amount of ice is so far below that of previous years that it really is cause for concern. The trend in decreasing ice cover seems to be getting stronger and stronger as time goes on. . . The longer this process continues, the less likely recovery becomes. The implications on global climate are not well known, but they have the potential to be quite large, since the Arctic ice cover exhibits a tremendous influence on our climate.

When there is less sea ice in the summer, the Arctic Ocean receives more heat. The warmer water makes it harder for the ice to recover in the winter, and, therefore, there is a higher likelihood that sea ice will retreat farther during the summer. This process repeats itself year after year.

The second study found that 2007 has seen an overall rise in melting over the entire Greenland ice sheet, with melting in high-altitude areas reaching the greatest extent ever observed, at 150 percent more than average. The amount of snow melted this year in Greenland would cover the surface size of the U.S. more than twice. Apparently melting icecaps are as bad as melting sea ice, only in a different way. This from Marco Tedesco at the Joint Center for Earth Systems Technology:

When snow melts at those high altitudes and then refreezes, it can absorb up to four times more energy than fresh, unthawed snow. This can affect Earth's energy budget by changing how much radiation from the sun is absorbed by the Earth versus that reflected back into the atmosphere. Refrozen snow can also alter the snow density, thickness and snow-water content. [Furthermore] increases in the overall melting trend over Greenland have an impact that stretches beyond its icy shores. Aside from contributing to direct sea level rise, melting especially along the coast can speed up glaciers since the meltwater acts like a lubricant between the frozen surface and the bedrock deep below. The faster glaciers flow, the more water enters the ocean and potentially impacts sea level rise.